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554066b8 | 1 | /* Create new context. |
dff8da6b | 2 | Copyright (C) 2002-2024 Free Software Foundation, Inc. |
554066b8 MS |
3 | |
4 | This file is part of the GNU C Library. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
17 | License along with the GNU C Library; if not, see | |
5a82c748 | 18 | <https://www.gnu.org/licenses/>. */ |
554066b8 MS |
19 | |
20 | #include <sysdep.h> | |
21 | #include <stdarg.h> | |
22 | #include <stdint.h> | |
23 | #include <ucontext.h> | |
24 | ||
25 | ||
26 | /* makecontext sets up a stack and the registers for the | |
27 | user context. The stack looks like this: | |
28 | ||
29 | +-----------------------+ | |
30 | | padding as required | | |
31 | +-----------------------+ | |
32 | sp -> | parameter 7-n | | |
33 | +-----------------------+ | |
34 | ||
35 | The registers are set up like this: | |
36 | %x0 .. %x7: parameter 1 to 8 | |
37 | %x19 : uc_link | |
38 | %sp : stack pointer. | |
39 | */ | |
40 | ||
41 | void | |
42 | __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...) | |
43 | { | |
44 | extern void __startcontext (void); | |
44bcba80 | 45 | uint64_t *sp; |
554066b8 MS |
46 | va_list ap; |
47 | int i; | |
48 | ||
44bcba80 | 49 | sp = (uint64_t *) |
554066b8 MS |
50 | ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size); |
51 | ||
52 | /* Allocate stack arguments. */ | |
53 | sp -= argc < 8 ? 0 : argc - 8; | |
54 | ||
55 | /* Keep the stack aligned. */ | |
44bcba80 | 56 | sp = (uint64_t *) (((uintptr_t) sp) & -16L); |
554066b8 MS |
57 | |
58 | ucp->uc_mcontext.regs[19] = (uintptr_t) ucp->uc_link; | |
59 | ucp->uc_mcontext.sp = (uintptr_t) sp; | |
60 | ucp->uc_mcontext.pc = (uintptr_t) func; | |
61 | ucp->uc_mcontext.regs[29] = (uintptr_t) 0; | |
62 | ucp->uc_mcontext.regs[30] = (uintptr_t) &__startcontext; | |
63 | ||
64 | va_start (ap, argc); | |
65 | for (i = 0; i < argc; ++i) | |
66 | if (i < 8) | |
44bcba80 | 67 | ucp->uc_mcontext.regs[i] = va_arg (ap, uint64_t); |
554066b8 | 68 | else |
44bcba80 | 69 | sp[i - 8] = va_arg (ap, uint64_t); |
554066b8 MS |
70 | |
71 | va_end (ap); | |
72 | } | |
73 | ||
74 | weak_alias (__makecontext, makecontext) |